How to Use a Dive Computer

Although dive computers are no replacement for having a safe dive plan, they can make scuba diving safer and eliminate some cumbersome, pen-and-paper dive table calculations. No two dive computers are alike, as each has its own features and control functions. Even so, all computers operate through the use of control buttons and automated features, and all computers are used to track the same diving data, so the procedures are largely the same regardless of the particular computer.

Instructions

    • 1

      Secure the computer properly before a dive. If you have a wristwatch computer, make sure the strap is snug and won't loosen too much as your wetsuit compresses at depth. Rig console computers so they do not drag on the sea bottom or become ensnared. If your computer has a wireless air-integration transmitter, make sure that transmitter is screwed snugly into the regulator.

    • 2

      Set the dive computer for mixed gas use if you will use oxygen-enriched gas (nitrox) or an exotic mixture for technical diving. Do this by pressing one or more of the control buttons on the computer to access the mixed gas sub-menu, picking the gas mixture if that is an option, and either picking a pre-set mix or adding/subtracting points from the gas mixture (increasing oxygen from 21 to 32 percent, for example). Skip this step if you are not using mixed gas.

    • 3

      Look at your computer once you are in the water to make sure it is working. Almost all dive computers activate automatically upon contact with the water. Abort the dive if your computer doesn't automatically activate, or if it displays garbled or inaccurate information, as it is likely broken or malfunctioning.

    • 4

      Monitor the basic information display during your initial descent. This always includes depth, water temperature, and usually either no-decompression time (the countdown to the time when your dive requires a decompression stop) or elapsed dive time, plus other information. This enables you to control your descent and check again that the computer is working properly.

    • 5

      Review the information on your computer during your dive. Sometimes this will require pressing one or more of the control buttons to change the display. Watch information such as depth (always displayed), elapsed dive time, no-decompression time and the prediction of how much nitrogen your body has absorbed (if your computer shows this information). If your computer is air-integrated (replaces your air pressure gauge), monitor how much air is left in your tank.

    • 6

      Check the temperature if you feel cold. Simply feeling cold is not an accurate indication of the local water temperature. If your wetsuit cannot cope with the water temperature, you must ascend to warmer water to avoid hypothermia.

    • 7

      Set the computer to include ascent data when you return to the surface. Monitor your ascent rate so you do not rise too quickly, and stop when you reach the depth range for a safety/decompression stop. Most dive computers automatically start a stop countdown upon reaching this point, so wait until the computer indicates your stop is over before returning to the surface.

    • 8

      Review the display upon reaching the surface for your log-book entry. Most computers display the data for dive log entries automatically, including total dive time and maximum depth. If you forget, you can retrieve this data later.

    • 9

      Look at your dive computer once you have taken off your gear and started your surface interval. If you intend to dive again that day, the computer will predict when you will be nitrogen-free. You can dive prior to reaching zero, but the computer will correspondingly adjust your no-decompression downwards.